Given two integer arrays arr_a and arr_b, both sorted in non-decreasing order, and two integers len_a and len_b representing the number of valid elements in arr_a and arr_b respectively, merge arr_b into arr_a so that arr_a contains the merged sorted array. arr_a has a length of len_a + len_b, with the first len_a elements valid and the remaining len_b elements set to 0 and ignored. arr_b has a length of len_b. The function should modify arr_a in-place to contain the merged sorted array.
Example 1
Input: arr_a = [4,7,9,0,0,0], len_a = 3, arr_b = [2,5,8], len_b = 3
Output: [2,4,5,7,8,9]
Explanation: Merge [4,7,9] and [2,5,8] into [2,4,5,7,8,9].
Example 2
Input: arr_a = [3,0,0], len_a = 1, arr_b = [1,2], len_b = 2
Output: [1,2,3]
Explanation: Merge [3] and [1,2] into [1,2,3].
Example 3
Input: arr_a = [0,0,0], len_a = 0, arr_b = [5,6,7], len_b = 3
Output: [5,6,7]
Explanation: Merge [] and [5,6,7] into [5,6,7].
Constraints
Case 1
Input: arr_a = [10,20,30,0,0,0], len_a = 3, arr_b = [15,25,35], len_b = 3
Expected: [10,15,20,25,30,35]
Case 2
Input: arr_a = [1,2,0], len_a = 2, arr_b = [3], len_b = 1
Expected: [1,2,3]
Case 3
Input: arr_a = [0], len_a = 0, arr_b = [-5], len_b = 1
Expected: [-5]
Case 4
Input: arr_a = [-2,0,0], len_a = 1, arr_b = [-1,0], len_b = 2
Expected: [-2,-1,0]
Case 5
Input: arr_a = [100,200,300,0,0], len_a = 3, arr_b = [150,250], len_b = 2
Expected: [100,150,200,250,300]